Western Church vs Roman Church

Western Church and Roman Church both are nouns.

Word	Noun	Adjective	Verb	Adverb
Western Church	Yes	No	No	No
Roman Church	Yes	No	No	No

As nouns, Western Church and Roman Church are synonyms defined as:

Western Church and Roman Church: the Christian Church based in the Vatican and presided over by a pope and an episcopal hierarchy

Other synonyms of Western Church include Church of Rome, Roman Catholic, Roman Catholic Church.

Western Church (noun)	Roman Church (noun)
the Christian Church based in the Vatican and presided over by a pope and an episcopal hierarchy	the Christian Church based in the Vatican and presided over by a pope and an episcopal hierarchy